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The increasingly restrictive legislation on the use of hazardous chemicals in lubricant formulation necessitates the use of less hazardous lubricant additives in the sheet metal forming industry. The tribological performance of calcium carbonate (CaCO3) as a green lubricant additive was evaluated in comparison to commercially available forming lubricants used in industry, some of which contain hazardous chemicals such as chlorinated paraffins to enable their function. The lubricants were tested by four-ball wear testing, four-ball weld load testing, and bending-under-tension. The ease of cleaning of surfaces formed with the different lubricants was evaluated by methods used in industry and the viscosity was evaluated using standard methods. The CaCO3 mixtures showed a better performance than commercial lubricants in four-ball wear testing, worse performance in four-ball weld load testing, worse cleanability, and a similar development of drawing force in bending-under-tension over 1000 consecutive strokes. When added to fully formed commercial lubricants, the particles degrade the performance of the lubricant in resisting adhesive wear but improve its capacity for resisting abrasive wear. Surfaces of formed parts after bending-under-tension testing with CaCO3 mixtures were scratched, while parts formed using commercial lubricants showed less scratching. The effect of including particles in a commercial lubricant depended on the application, either degrading it or improving it. It is therefore clear that the use of solid particles as lubricant additives should be constrained to selected applications where abrasive wear is a dominant wear mechanism. [ABSTRACT FROM AUTHOR]

Organic coatings containing solid lubricants effectively prevent contact between recycled aluminum alloy surfaces and molds, thereby preventing damage caused by impurities. PVB-based easily removable coatings show promise in the stamping industry, but there is scarce research on the interactions of various lubricating additives within easily removable binder systems and their lubrication effects. This paper primarily concentrates on the synthesis of PVB-based composite coatings containing PTFE and MoS2. It delves into the synergistic lubrication mechanism of MoS2 and PTFE on mold steel, as investigated through cupping and tribological tests. The results show that the compounded coating exhibits superior dispersion, lubrication performance, tribological properties, and can withstand higher stamping loads compared to single-component coatings. MoS2 demonstrates exceptional extreme pressure performance and enhances the transfer capability of the coating. PTFE reduces the friction coefficient while minimizing coating adhesion to the die surface. This study provides a theoretical foundation for selecting solid lubricants in organic thin coatings for stamping lubrication. [ABSTRACT FROM AUTHOR]

Bolted joints are used extensively in mechanical engineering due to their reusability, appearance, and strength advantages. In different industrial applications, the separated mechanical components are clamped together during the assembly using a tightening process. Estimating precisely the initially achieved clamping force is a persistent problem for providing a secure and reliable connection for a particular design. However, the nut coefficient is one of the exploratory methods used for this purpose. This paper aims to investigate how the nut coefficient of a bolted joint is influenced by factors such as bolt/nut surface treatment and the presence of lubrication at joint contact surfaces throughout the cyclic joint assembly/disassembly process, serving as a simulation for real-life maintenance operations where the same bolt/nut are reused. Torquing cycles were introduced to bolted joints with two surface finishes and four lubrication conditions. The experiments were conducted on bolts at room temperature according to ISO16047. The nut coefficient was calculated for bolt sizes M6*1, M8*1.5, and M10*1.5. The results were analyzed using the analysis of variance and Taguchi method L32 for estimating the contribution of the different factors on the nut coefficient. It was found that the lubrication was the most significant parameter affecting the nut factor regardless of the bolt size. Also, a case study was conducted to investigate the underlying reasons behind the significance of lubrication in influencing the nut coefficient across different bolt sizes. [ABSTRACT FROM AUTHOR]

Due to the impending depletion of petroleum reserves and environmental worries, the creation of bio-lubricants is a compelling subject of research. With the use of tertiary butylhydroquinone (TBHQ) and Eichhornia crassipes carbon nanotubes (EC-CNTs), this work intends to create an effective sunflower oil-based bio-lubricant and analyze its tribological performance using a ball-on-disk tribo-meter. Different additive concentrations were blended to create the bio-lubricant. The tribological analysis was conducted in terms of coefficient of friction (COF), wear rate, wear scar diameter, surface roughness for different speed, load and temperature. The morphology shows good structures of the employed additives, TGA revealed good thermal resistance, FT-IR indicated good compatibility with needed functional groups. Under tribological test at 1500 rpm, inclusion of additives (SFO + 0.9wt.% EC-CNTs + 0.3wt.% TBHQ) demonstrated good enhancement on sunflower lubrication, thus showing COF and wear rate values of 0.058 and 13.5 10-9 mm3.m-1.N-1 against base sunflower COF and wear rate values of 0.074 and 15.5 *10-9 mm3.m-1.N-1. Under surface roughness, application of additives lowers the roughness on the lubricated surfaces (SFO + 0.9 wt.% EC-CNTs = 0.447 µm), (SFO + 0.3 wt.% TBHQ = 0.453 µm), thus shows smoothest when blended the two additives together (SFO + 0.9 wt.% EC-CNTs + 0.3 wt.% TBHQ = 0.244 µm), against base SFO value of 0.522 µm. The use of additives in SFO shows synergistic result via nano-lubricant tribo-film formation resulting in commended outcome in all the conditions tested. [ABSTRACT FROM AUTHOR]

Stern tube slide bearing of the shaft line of the ship’s propulsion system causes losses during operation. Friction and material wear of the tribosystem occur. One of the reasons is the different navigating regimes of the ship, which have an influence on the formation of the velocity field on the ship’s propeller. The variable velocity field defines the magnitude and the position of the thrust force. The methodology presented in this paper is based on the fact of the existence of the eccentricity of the thrust force, i.e. loads due to the action of the moment of the eccentric thrust force. Due to the changing position of the thrust force, the curvature of the elastic line of the sleeve inside the stern tube bearing, which is mostly spatial, changes. Spatial elastic line of the sleeve has an influence on the working area of the slide bearing. Therefore, the importance of a sufficient thickness of the lubricant layer for lubrication in relation to these changes was highlighted. In this paper, this is the initial criterion for the selection of materials and lubricants of the stern tube bearing. An equally important criterion would be to define the possible harmful impact of lubricant leakage with particles of bearing bush material on the ecosystem. In order to facilitate the whole process, the simplified analytical model is presented, which can be used in the initial stage of stern tube bearing selection. Such a model allows a simpler analysis of the influence of the elastic line on the condition of the stern tube bearing due to the loading by the weight of the ship’s propeller and by the moment of the eccentric thrust force. The procedure for the initial selection of the stern tube bearing created by this methodological approach could have its practical application. For this reason, the paper analyzed different navigating regimes and their influence on the working area of the stern tube slide bearing. The obtained results can be useful in the selection of materials and lubricants for the stern tube bearing tribosystem. [ABSTRACT FROM AUTHOR]

This study is dedicated to assessing the friction properties and vibration characteristics of the friction process of a hard alloy based on tungsten carbide with an experimental binder (5.65% Co + 1.8% Mo + 0.6% Ti), created based on the standard VK8 grade by partially replacing cobalt with a Mo+Ti metal group. Tribological tests were carried out without the use of a lubricant according to the "pin-on-disk" scheme during frictional interaction with steels 15Kh2NMFA and 10GN2MFA at constant load and sliding velocity. During the experiments with steel 10GN2MFA, growth of the intermediate layer in the gap between the elements of the friction pair was observed, subsequently resulting in a wider spacing between the friction bodies over time. However, no statistically significant differences were found in the gap thickness and/or roughness of the friction surfaces depending on the hard alloy grade, while the friction coefficient of the experimental composition was lower. Similarly, no significant differences in the friction surface microrelief changes on the counterbodies were found when studying the frictional interaction between samples and steel 15Kh2NMFA. However, the friction dynamics of the experimental hard alloy is characterized by lower friction coefficients and smaller thickness of the intermediate layer, as well as reduced amplitude of vibrations generated by the tribosystem dynamics itself. [ABSTRACT FROM AUTHOR]

Poly (2-methacryloyloxyethyl phosphorylcholine) (PMPC), as a highly hydrophilic as well as biocompatible material, has been widely used in biomedical applications. In this study, the friction reduction and wear resistance of HXLPE were improved by grafting PMPC on its surface. However, the PMPC will be sheared off during friction, which is difficult to meet the long-term service requirements of artificial joints. This can be achieved by improving the lubrication environment to minimize PMPC shedding. To simulate the human lubrication environment, free PMPC (lubrication factor) and Cu2+ (transition group metal ion catalyst) were added to neonatal bovine serum (NBCS). When the friction pair consisting of grafted PMPC-modified HXLPE and Cu/ZrO2 ceramics is rubbed therein, the grafted PMPC interacts with the free PMPC, while Cu2+ catalyzes the oxidative hydrolysis of serum proteins into carbon-containing small molecules and adsorbs on the surface of the Cu/ZrO2 ceramics to form a carbon-rich lubrication layer. The composite lubrication layer consisting of grafted-free PMPC and carbon-rich lubrication layer provides good load-bearing and lubrication properties at the friction interface. And the wear rate is reduced by 45% compared to rubbing in deionized water. This technique can reduce the shedding of grafted PMPC state and improve the load-bearing performance of the interfacial lubrication layer, thus reducing the wear of HXLPE and prolonging the service life of the artificial joint. [ABSTRACT FROM AUTHOR]

The rice bran and rice bran wax of the KJ CMU107 rice strain were investigated as potential tablet lubricants in a directly compressed tablet formulation. Stabilized full-fatted rice bran (sFFRB), stabilized defatted rice bran (sDFRB), and rice bran wax (RBW) extracted and purified from crude rice bran oil (cRBO) were tested. Two commercial lubricants, including magnesium stearate (MGS) and hydrogenated cottonseed oil (HVO), were employed as the standards in the formulated mixtures, which contained spray-dried rice starch (SDRS) as a diluent. The tableting was carried out for each formulation, and the obtained tablets were physically and mechanically evaluated. Among the parameters investigated were the general appearance, ejection force, weight variation, hardness, friability, and disintegration time. The powder flow was also determined for each formulation. The results showed that the tablet ejection forces for all the lubricated formulations (58–259 N) were significantly lower than that of the non-lubricated control formulation (349 N). The use of sFFRB as a lubricant at 0.5–2.0% w/w could lower the ejection force up to 78%, but the hardness reduced so drastically that the formulations failed the friability test due to the chipping of the tablets' edges. Moreover, sDFRB performed significantly better as the use at 0.5–1.0% w/w in the formulation helped to lower the ejection forces by up to 80% while maintaining the changes in the tablet hardness within 10%. RBW functioned effectively as a tablet lubricant at a concentration of 0.5% w/w, yielding tablets with good strength comparable to standard HVO lubricant while helping to reduce the ejection force by 82%. In formulations with good lubrication, i.e., friability < 1%, the powder flow was improved, and the tablet disintegration times were within the same range as the control and HVO formulations. In conclusion, sDFRB displayed a lubricant property at concentrations between 0.5 and 1.0% w/w, with slightly negative effects on the tablet hardness. RBW from KJ CMU107 rice was an effective tablet lubricant at 0.5% w/w, with no effect on tablet hardness. Both materials can be further developed for use as commercial lubricants in direct compression. [ABSTRACT FROM AUTHOR]

We designed an inquiry activity to investigate the question, 'Is water a lubricant?' Placing the same object on surfaces of three different materials, we observed the effect of adding a small amount of water on the coefficient of static friction, μ s . Up to 1 ml of water was added. The results of each surface were graphed and compared with one another. In general, our findings show that the addition of water serves to increase μ s up to a certain point, before decreasing it. The experiment can be easily replicated in a secondary school science lab. It presents two seemingly opposing phenomena, but they both hold because they occur within their respective boundary conditions. [ABSTRACT FROM AUTHOR]

The article discusses the genitourinary syndrome of menopause (GSM), a condition where estrogen is absent in genital tissues postmenopausal. It reports a randomized controlled trial comparing vaginal estrogen, vaginal moisturizer, and placebo for treatment. It mentions that the most common symptom is vaginal dryness and pain with penetration. It emphasizes that treatment options include over-the-counter lubricants and vaginal estrogen.

Regular lard (RL) was chemically modified into isopropyl‐branched lard (BL). The isopropyl group was introduced into the triglyceride structure via a reaction of carbon–carbon double with isopropyl bromide in presence of ethylaluminum sesquichloride. The reaction was confirmed with gas chromatography–mass spectroscopy, nuclear magnetic resonance, infrared spectroscopy. The physical, tribological and chemical properties of the RL, BL and their blendings in polyalphaolefin (PAO) and high‐oleic sunflower oil (HOSuO) were investigated. The BL exhibited better solubility both in HOSuO and PAO than RL. Compared to RL, BL exhibited higher density, viscosity, improved oxidative stability and cold flow properties both as a neat material and blendings in HOSuO or PAO. However, BL displayed lower viscosity index (197 vs. 162) compared to RL. Both RL and BL displayed similar lubricity as HOSuO and showed potential such as a good lubricity additive in PAO even in small amounts (~10 wt%). This study reveals introducing alkyl branching into lard can lead to improved physico‐chemical properties and lubrication performance. [ABSTRACT FROM AUTHOR]

This study investigated the potential of inedible mustard oil (MO) (Brassica juncea) as a suitable bio-lubricant for enhanced thermal, oxidative stability, and tribological performance. To improve the MO's oxidative stability, it was subjected to a chemical epoxidation reaction, forming epoxidized mustard oil (EMO). The MO and EMO were evaluated for viscosity, functional groups, wettability, oxidative stability, thermal stability, friction, and wear performance. The epoxidation process resulted in nearly doubling the oxidative stability, as well as improving the thermal stability of the MO. Results showed that the EMO exhibited better lubricating properties than the MO, including lower friction and wear. To further improve the lubrication performance of the EMO, solid lubricant additives (SLAs) were incorporated in various concentrations. These SLAs were graphene nanoplatelets (GNP) and hexagonal boron nitride (hBN). The GNP and hBN nano lubricants reduced friction by 31% and 13% compared to the EMO. The same nano lubricants also lowered wear by 73% and 51% relative to the EMO. The underlying mechanisms behind the improvement in the friction and wear performance were discussed. The EMO can be considered as a suitable base stock for renewable and sustainable energy applications. [ABSTRACT FROM AUTHOR]

The dynamic behavior of the pump-turbine thrust bearing is important to the safety operation of the unit. This paper analyzed the lubrication and energy dissipation mechanism of pump-turbine thrust bearing during load-rejection based on the thermo-hydrodynamic model. The results show that the variation of the axial force and the maximum pad surface pressure is basically consistent with that of the inclination of the pad surface. The change of the friction loss is consistent with the change of rotational speed, while the change of pad surface temperature is affected by the combination of pad inclination and rotational speed. The chaotic flow in the oil tank is accompanied by different forms of vortices, such as Taylor vortices, vortex pairs, and Karman vortices, and results in a significant asymmetry in the pressure distribution. The flow in the bearing pad groove has an effect on the energy dissipation in the oil film. This paper provides a theoretical basis for the design and optimization of thrust bearings, and provides a reference for solving the problems of wear, oil mist, and other related problems of thrust bearings in engineering. [ABSTRACT FROM AUTHOR]

The long-term wear of the piston/cylinder pair is the main failure reason for axial piston pumps. In this paper, the dynamics of textured films to enhance the lubrication performance of piston/cylinder pairs is investigated systematically. The oil film is divided into three regions: the head region, the texture region, and the tail region. The Reynolds equation is used to predict the dynamics, which includes the carrying capacity and the friction. Influences of the texture geometries and the working conditions are presented in sequence. The results show that the texture enhances the lubrication performance by the collective effect. A shorter head length and a larger area ratio always benefit the lubrication performance, while increasing the texture region length does not always lead to positive effects, and the cell length is found to have negligible influences. The texture effect is found to be enhanced with larger shearing velocities and to be restrained with higher inlet pressures. It is also shown that the texture is effective for small inclination angles. Furthermore, a one-dimensional model is performed to unravel the mathematical mechanism, and an explicit expression is given for the texture region length. [ABSTRACT FROM AUTHOR]

Genitourinary syndrome of menopause encompasses the group of urogenital signs and symptoms resultant from hypoestrogenism, including genital dryness, burning or irritation, sexual discomfort, pain or dysfunction, and urinary urgency, dysuria, and recurrent urinary tract infections. Genitourinary syndrome of menopause can have a profound impact on well-being, functioning, and quality of life in postmenopausal women. Treatment includes vaginal moisturizers and lubricants geared towards providing symptomatic relief; hormonal treatments which promote epithelial thickening and production of vaginal secretions; and pelvic floor physical therapy along with behavioral therapies that address pelvic floor hypertonicity and psychosocial factors. [ABSTRACT FROM AUTHOR]

The current work investigates the conversion of neem seed oil to biolubricant. Furthermore, calcium oxide was prepared from egg shell by calcination and activated with phosphuric acid solution. The activated calcium oxide produced was characterized using FT-IR and TGA. The neem seed oil was transesterified using methanol over activated calcium oxide derived from egg shell as catalyst to produce methyl esters (biodiesel), which was again transestrified with trimethylolpropane (TMP) under reflux at different reaction conditions to produce the target biolubricant and characterized using FT-IR and GC-MS. using the same activated calcium oxide prepared from egg shell as catalyst. Optimization of process parameters for tranesterification of neem seed oil was determined by Response surface based on Box-Beinkhen design. The optimum yield of the biolubricnat (79.60%) was achieved at the temperature, catalyst dose and reaction time of 150 0C, 0.75%wt and 3 hours respectively. [ABSTRACT FROM AUTHOR]

Broad use of lightweight aluminium alloy parts in automobile manufacturing, aerospace, electronic communication, and rail transit is mainly formed through deep drawing process. Deep drawing friction is a key boundary condition for controlling the forming quality of aluminium alloy parts. However, due to the oxidation and adhesion tendency of aluminium alloys, the tribological situations of aluminium alloy deep drawing (AADD) system is more complicated than those of traditional deep drawing of steel sheets. Therefore, the study of AADD friction is essential for manufacturing high-performance aluminium alloy parts. Herein, aiming to provide a valuable reference for researchers in related fields, a comprehensive review of AADD friction is provided, including friction mechanism, influencing factors, friction measurement, friction model, friction simulation, and lubrication-free friction control. Finally, a brief conclusion and several current challenges were discussed. [ABSTRACT FROM AUTHOR]

Carbon quantum dots (CQDs) have already demonstrated their utility as lubricant additives, and non-contact temperature sensing based on CQDs offers considerable potential for condition monitoring in mechanical, electrical, and other fields, as well as lubrication-temperature multifunctional applications in lubricants. In this paper, we have successfully synthesized and designed high-brightness carbon quantum dots/polyvinyl alcohol (PVA) temperature sensor thin film and dispersions of CQDs in a liquid paraffin lubrication system. Based on fluorescence intensity and the fluorescence intensity ratio, the carbon quantum dot/PVA film exhibited exponential temperature-dependent properties with a wide applicability range, a high goodness of fit (R2 > 0.99), and high relative thermal sensitivity (relative sensitivities of 1.74% K−1 and 1.39% K−1 for fluorescence intensity and fluorescence intensity ratio, respectively). In addition, based on the fluorescence intensity, the CQDs exhibited a wide temperature range (20–90 °C), a high goodness of fit (R2 > 0.99), and higher sensitivity (2.84% K−1) in a liquid paraffin lubrication system, which reflects the temperature responsive properties of carbon quantum dots as additives in lubrication systems. These findings provide convenient and effective possibilities for the sensing and monitoring of carbon quantum dots and their multifunctional applications under lubrication systems. [ABSTRACT FROM AUTHOR]

Bio-lubricants are the future of lubricants as a substitute for mineral lubricants; however, bio-lubricants have drawbacks, such as poor thermal-oxidative stability. In addition, during the friction process, the temperature of the lubricant increases, so the lubricant must have good thermal conductivity to conduct heat to the environment. To combat the drawbacks of bio-lubricants, some additives have been used to improve their performance as lubricants. Composites of carboxymethyl cellulose (CMC)/MXene and Span 60 as surfactants were used as additives in CPO with different compositions. The physicochemical properties of the addition of CMC/MXene and Span 60 in CPO have changed, including kinematic viscosity, TAN, thermal conductivity, and fatty acids, which have a positive impact on lubrication performance in terms of reducing oxidation processes and increasing thermal conductivity. From fatty acid composition tests and FTIR analysis, the additives work to suppress the oxidation process. A pin-on-disk test was performed to evaluate the tribological performances of bio-lubricants. The results show that CM 10 SP (0.5% wt of CMC and MXene and 1% wt Span 60) demonstrated a significant decrease in CoF and wear rate by 49% and 74%, respectively, at a load of 50 N and a speed of 1400 rpm compared to CPO without additives. An interface layer of CMC/MXene and Span 60, separating two surfaces, could induce wear on the surface of the disk and pin. [ABSTRACT FROM AUTHOR]

Peter Jost is known to the international tribology community as the father of the subject—'the man who made the world spin a little easier'. He was the author of the eponymous 'Jost Report', the report of the Working Group set up in 1964 to investigate the state of lubrication education and research in the UK. Over the following five decades, up to his death in 2016, he was tireless in extolling the importance of tribology to manufacturing efficiency, energy conversion and environmental sustainability. He was instrumental in establishing the International Tribology Council and its prestigious gold, silver and bronze medals. Jost was himself the recipient of numerous national and international awards. In 1976, he was the President of the Institution of Production Engineers, and in 2013, he received the Sustained Achievement Award from the Royal Academy of Engineering. What is less well known is the story behind the Jost report—what was it that led the recently elected Labour government and its newly established Ministry of Technology to investigate lubrication and to choose Jost to lead the investigating panel? The story illustrates the combination of serendipity and determination on which success can so often depend. [ABSTRACT FROM AUTHOR]

To enhance the performance and reduce the amount of ester-based lubricants used in weak gel drilling fluids, a shear dynamics simulation under extreme pressure conditions was employed to refine the formulation of the base oil and pressure additives. The simulation results were validated using fatty acid methyl, ethyl, and butyl esters. Fatty acid methyl ester demonstrated the lowest temperature increase and the highest load-bearing capacity post-shear. The four-ball friction test revealed that methyl oleate had a coefficient of friction of 0.0018, approximately a third of that for butyl oleate, confirming the simulation's accuracy. By using methyl oleate as the base oil and oleamide as the pressure-resistant component, the optimal shear stress was achieved with a 10% addition of oleamide. A lubricant composed of 90% methyl oleate and 10% oleamide was tested and showed a coefficient of friction of 0.03 when 0.5% was added to bentonite slurry, indicating a strong lubricating film. Adding 1% of this lubricant to a low gel drilling fluid system did not affect its rheological properties, and the gel structure remained stable after seven days of aging. Field tests at the Fu86-3 well in the Jiangsu Oilfield of Sinopec confirmed that adding 1% of the ester-based lubricant to the drilling fluid significantly improved drilling efficiency, reduced drag by an average of 33%, and increased the drilling rate to 22.12 m/h. This innovation effectively prevents drilling complications and successfully achieves the objectives of enhancing efficiency. [ABSTRACT FROM AUTHOR]

Grease is made up of a lubricant (typically petroleum oil) and a thickener (soap). The study focus on the production and characterization of grease for automobile and industrial machinery. The practicality and application of the technique were examined in order to decide whether the lithium grease produced from palm kernel oil might be used as an environmental friendly alternative to conventional grease. The aforementioned objective was achieved by mechanically extracting oil from palm kernel nuts. Lithium grease was produced through the saponification of lithium oxide with palm kernel oil. The lithium grease melting and drop points, flash point, and ash content were discussed. According to the study's findings, the lithium grease produced results that were acceptable and in accordance with ASTM standards, with the exception of its ash content, which will cause the grease to break off under pressure. [ABSTRACT FROM AUTHOR]

The rails and wheels are one of the most critical and expensive components of railway transport, and any problem could generate numerous consequences. The ability to manage friction at the wheel-rail interface currently represents one of the greatest challenges and one of the most powerful tools in railway engineering. The application of friction modifiers, lubricants, and friction enhancers to friction control have been the focus of extensive research of wheel-rail systems. The friction modifier (FM) provides a targeted coefficient of friction (COF) of 0.3–0.4. Currently, the laboratorial retentivity tests conducted by manufacturers do not describe the standards used, neither the surface integrity before the FM application. This work studies the influence in the retentivity of the different surface integrity states before application of FM using a twin-disk test. It will be possible to define the surface condition necessary for the application of FMs in retentivity tests, using a twin-disk tribometer. A commercial friction modifier was applied before the test (zero cycles) and after 500; 1,000; 1,500; 2,000; 3,000; 4,000; and 5,000 dry cycles, ending the tests when the coefficient of traction (COT) reached 0.4. To compare the retentivity of different FMs, a complete standardization of the twin-disk test is essential, applying the FM in a controlled amount, with over 2,000 dry cycles, and using a disk with controlled initial roughness. [ABSTRACT FROM AUTHOR]

Friction is one of the main phenomena accompanying sheet metal forming methods, affecting the surface quality of products and the formability of the sheet metal. The most basic and cheapest way to reduce friction is to use lubricants, which should ensure the highest lubrication efficiency and at the same time be environmentally friendly. Due to the trend towards sustainable production, vegetable oils have been used in research as an alternative to petroleum-based lubricants. The analysis of friction in sheet metal forming requires an appropriate tribotester simulating the friction conditions in a specific area of the sheet metal being formed. Research has used a special strip drawing tribometer, enabling the determination the value of the coefficient of friction in the blankholder zone in the deep drawing process. Quantitative analysis of the friction phenomenon is necessary at the stage of designing the technological process and selecting technological parameters, including blankholder pressure. This article presents the results of friction testing of 1.0338 (DC04) steel sheets using a strip drawing test. The experimental tests involved pulling a strip of sheet metal between two countersamples with a rounded surface. The tests were carried out on countersamples with different levels of roughness for the range of contact pressures occurring in the blankholder zone in the deep drawing process (1.7–5 MPa). The values of the coefficient of friction determined under dry friction conditions were compared with the results for edible (corn, sunflower and rapeseed) and non-edible (Moringa, Karanja) vegetable lubricants. The tested oils are the most commonly used vegetable-based biolubricants in metal forming operations. Multi-layer artificial neural networks were used to determine the relationship between the value of the contact pressure, the roughness of the countersamples, the oil viscosity and density, and the value of the coefficient of friction. Rapeseed oil provided the best lubrication efficiency during friction testing for all of the tested samples, with an average surface roughness of Sa 0.44–1.34 μm. At the same time, as the roughness of the countersamples increased, a decrease in lubrication efficiency was observed. The lowest root mean squared error value was observed for the MLP-4-8-1 network trained with the quasi-Newton algorithm. Most of the analysed networks with different architectures trained using the various algorithms showed that the kinematic viscosity of the oil was the most important aspect in assessing the friction of the sheets tested. The influence of kinematic viscosity on the value of the coefficient of friction is strongly dependent on the surface roughness of the countersamples. [ABSTRACT FROM AUTHOR]

The purpose of this paper was to study the evolution and dynamic characteristics of the helical gear system co-existence response considering the occurrence of de-meshing and reverse impact under lubrication conditions. The double-three tooth alternate meshing model of a helical gear was established, and the time-varying geometric parameters, motion parameters, and load distribution of positive meshing and reverse impact were analyzed, respectively. The variation of oil film parameters and the coupling between oil film stiffness and meshing stiffness of a gear system were studied according to the equivalent lubrication model of a helical gear. Considering the phenomenon that the meshing state changed from positive meshing to de-meshing and reverse impact, the dynamics model was established. The global bifurcation diagram, the attraction domain, the phase portrait, and the Poincaré section were used to analyze the evolution of a coexistence response and dynamic characteristics with helical gear system parameters. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to investigate the preparation of AlN and Al2O3, as well as the effect of nano-AlN and nano-Al2O3, on friction and wear properties of copper-steel clad plate immersed in the lubricants. Design/methodology/approach: Nano-AlN or nano-Al2O3 (0.1, 0.2, 0.3, 0.4 and 0.5 Wt.%) functional fluids were prepared. Their tribological properties were tested by an MRS-10A four-ball friction tester and a ball-on-plate configuration, and scanning electron microscope observed the worn surface of the plate. Findings: An increase in nano-AlN and Al2O3 content enhances the extreme pressure and anti-wear performance of the lubricant. The best performance is achieved at 0.5 Wt.% of nano-AlN and 0.3 Wt.% of nano-Al2O3 with PB of 834 N and 883 N, a coefficient of friction (COF) of approximately 0.07 and 0.06, respectively. Furthermore, the inclusion of nano-AlN and nano-Al2O3 particles in the lubricant enhances its extreme pressure performance and reduces wear, leading to decreased wear spot depth. The lubricating effect of the nano-Al2O3 lubricant on the surface of the copper-steel composite plate is slightly superior to that of the nano-AlN lubricant, with a COF reaching 0.07. Both lubricants effectively fill and lubricate the holes on the surface of the copper-steel composite plate. Originality/value: AlN and Al2O3 as water-based lubricants have excellent lubrication performance and can reduce the COF. It can provide some reference for the practical application of nano-water-based lubricants. Peer review: The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2023-0255/ [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to investigate the effects of nanoadditive lubricants on the vibration and noise characteristics of helical gears compared with conventional lubricants. The experiment aims to analyze whether nanoadditive lubricants can effectively reduce gear vibration and noise under different speeds and loads. It also analyzes the sensitivity of the vibration reduction to load and speed changes. In addition, it compares the axial and radial vibration reduction effects. The goal is to explore the application of nanolubricants for vibration damping and noise reduction in gear transmissions. The results provide a basis for further research on nanolubricant effects under high-speed conditions. Design/methodology/approach: Helical gears of 20CrMnTi were lubricated with conventional oil and nanoadditive oils. An open helical gearbox with spray lubrication was tested under different speeds (200–500 rpm) and loads (20–100 N·m). Gear noise was measured by a sound level meter. Axial and radial vibrations were detected using an M+P VibRunner system and fast Fourier transform analysis. Vibration spectrums under conventional and nanolubrication were compared. Gear tooth surfaces were observed after testing. The experiment aimed to analyze the noise and vibration reduction effects of nanoadditive lubricants on helical gears and the sensitivity to load and speed. Findings: The key findings are that nanoadditive lubricants significantly reduce the axial and radial vibrations of helical gears under low-speed conditions compared with conventional lubricants, with a more pronounced effect on axial vibrations. The vibration reduction is more sensitive to rotational speed than load. At the same load and speed, nanolubrication reduces noise by 2%–5% versus conventional lubrication. Nanoparticles change the friction from sliding to rolling and compensate for meshing errors, leading to smoother vibrations. The nanolubricants alter the gear tooth surfaces and optimize the microtopography. The results provide a basis for exploring nanolubricant effects under high speeds. Originality/value: The originality and value of this work is the experimental analysis of the effects of nanoadditive lubricants on the vibration and noise characteristics of hard tooth surface helical gears, which has rarely been studied before. The comparative results under different speeds and loads provide new insights into the vibration damping capabilities of nanolubricants in gear transmissions. The findings reveal the higher sensitivity to rotational speed versus load and the differences in axial and radial vibration reduction. The exploration of nanolubricant effects on gear tribological performance and surface interactions provides a valuable reference for further research, especially under higher speed conditions closer to real applications. Peer review: The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2023-0220/ [ABSTRACT FROM AUTHOR]

This article uses minimum quantity lubrication technology to replace traditional machining. A mixed nanofluid cutting fluid MNFCF was prepared using base oil, LINN 4444 ionic liquid, and nanoparticles as raw materials, and its tribological and drilling properties were studied. In the tribological performance test, the friction coefficient of the mixed nanofluid MNFCF is only 0.13. Compared with the control, the wear amount of MNFCF has decreased by about 75%, indicating that MNFCF has good anti friction and wear performance. Similarly, in the drilling performance test, the drilling test temperature of MNFCF cutting fluid decreased by 36.5% compared to the same. After drilling and testing, there was almost no BUE, BUL, or wear on the surface of the tool, with only a small amount of adhesive observed. The results indicate that MNFCF has good potential in drilling Inconel 690 high-temperature alloy. [Display omitted] • New type of cutting fluid was synthesized and used as drilling cutting fluid for nickel 690. • MNFCF cutting fluid has excellent drilling performance. • MNFCF with excellent tribological, cooling and drilling properties. • Excellent drilling performance is nanomaterials and lubricating films work synergistically. [ABSTRACT FROM AUTHOR]

Extensive research in smart manufacturing and industrial grinding has targeted the enhancement of surface roughness for diverse materials including Inconel alloy. Recent studies have concentrated on the development of neural networks, as a subcategory of machine learning techniques, to predict non-linear roughness behavior in relation to various parameters. Nonetheless, this study introduces a novel set of parameters that have previously been unexplored, contributing to the advancement of surface roughness prediction for the grinding of Inconel 738 superalloy considering the effects of dressing and grinding parameters. Hence, the current study encompasses the utilization of a deep artificial neural network to forecast roughness. This implementation leverages an extensive dataset generated in a recent experimental study by the authors. The dataset comprises a multitude of process parameters across diverse conditions, including dressing techniques such as four-edge and single-edge diamond dresser, alongside cooling approaches like minimum quantity lubrication and conventional wet techniques. To evaluate a robust algorithm, a method is devised that involves different networks utilizing various activation functions and neuron sizes to distinguish and select the best architecture for this study. To gauge the accuracy of the methods, mean squared error and absolute accuracy metrics are applied, yielding predictions that fall within acceptable ranges for real-world industrial roughness standards. The model developed in this work has the potential to be integrated with the Industrial Internet of Things to further enhance automated machining. [ABSTRACT FROM AUTHOR]

Polytetrafluoroethylene (PTFE) has been widely used as a lubrication additive for reducing friction and wear; however, the hydrophobic nature of PTFE restricts its application in eco-friendly water-based lubrication systems. In this study, for the first time, we designed novel PTFE@silica Janus nanoparticles (JNs) to meet the requirement for additives in water-based lubricants, which have excellent dispersion stability in water attributed to the unique amphiphilic structure. By introducing the lubrication of the aqueous dispersion of the JNs with a concentration of 0.5 wt%, the coefficient of friction (COF) and wear volume were reduced by 63.8% and 94.2%, respectively, comparing to those with the lubrication of pure water. Meanwhile, the JNs suspension also exhibits better lubrication and wear-resistance performances comparing to commercial silica and PTFE suspensions. The excellent tribological behaviors of PTFE@silica JNs as nano-additives could be attributed to the synergetic effect of the two components, where the PTFE provided lubrication through the formed tribofilms on the friction pairs, and the rigid silica further enhanced the wear-resistance performance. Most importantly, the unique structure of JNs makes it possible to use PTFE as an additive in water-lubrication systems. Our study shed light on the design and application of novel JNs nanomaterials as additives to meet the requirements of future industrial applications. [ABSTRACT FROM AUTHOR]

This study investigates the thermal generation dynamics in the spindle unit of a CNC milling machine. The main objective is to analyze the heat transfer from the bearings to the housing during operation, using simulations and experiments. An air-oil-cooled lubrication system is employed, which enables the airflow to dissipate some of the heat produced. Before conducting the experiment, heat generation and transfer are accurately predicted. The air-oil mixture, formed by pressurized air atomizing oil droplets, is effective in cooling high-temperature regions. A spindle ER16-80SK 24k is integrated with a CNC machine for realtime data acquisition, including parameters such as spindle speed and temperature. The results show significant temperature rises in all bearings, which reach a steady state after an hour of operation. There are noticeable differences in range, from 6.1% to 43.4%, between the experimental and simulated maximum temperatures, indicating possible real factors not considered in the simulation. The environmental impacts of oil particle emission are also discussed, which require proper ventilation management during operations. This research provides valuable insight into the thermal dynamics of CNC milling machine spindles and establishes a solid basis for further research and development in this important field of machining technology. [ABSTRACT FROM AUTHOR]

This research shows the antifriction and antiwear synergies between a phosphonium ionic liquid (IL) and f-WS2 and f-SiO2 nanoparticles (NPs) as additives of a base oil with low viscosity (PAO6). Mass concentrations of 0.1 wt% nanoadditives and 1% IL were selected to formulate the nanolubricants. Pure sliding and rolling–sliding friction tests were performed at 120 °C, finding great friction reductions in comparison with the PAO6 base oil, specifically for the double hybrid nanolubricant (PAO6 + 1 wt% IL + 0.1 wt% f-WS2 + 0.1 wt% f-SiO2). Regarding the wear produced, the greatest antiwear behavior was also achieved for the double hybrid nanolubricant (width reduction of 48% and worn area decrease of 84%). Furthermore, by means of Raman microscopy and roughness examination of the worn surfaces, it can be proposed that the lubrication mechanism of doubled hybrid nanolubricants could be supported by the adsorbed tribofilm (IL and f-WS2) as well as the mending effects (f-WS2 and f-SiO2). [ABSTRACT FROM AUTHOR]

Recent green manufacturing demands have boosted the development of new biodegradable lubricants to replace petroleum-based lubricants. In this regard, water-based lubricants have been at the vanguard of recent research for a wide range of industrial applications, including metalworking fluids (MWFs). In this work, we present an experimental investigation on the performance of novel green MWFs based on aqueous nopal mucilage solutions. For this, fully biodegradable solutions with different mucilage concentrations (2.29, 4.58, and 6.85 mg/mL) were evaluated in terms of rheological, tribological, thermal stability, and turning (minimum quantity lubrication) performance and compared to a commercial semisynthetic oil-based MWF (Cimstar 60). Mucilage solutions exhibited viscoelastic shear-thinning behavior, which was enhanced along with mucilage concentration. The solution with the highest mucilage content studied resulted in the lowest wear, friction, and temperature in comparison to the other solutions and neat water in extreme pressure four-ball tests and a similar level of lubricity as compared to the commercial MWF in cutting tests. This performance is associated with the enhanced viscosity and elasticity of the solution, as well as the contents of lipids with fatty acids in the mucilage. Overall, the present results reveal the relevance of the viscoelastic behavior of the lubricant, elasticity in particular, in lubrication processes and point to nopal mucilage as an effective green additive to produce innocuous MWFs. [ABSTRACT FROM AUTHOR]

Developing a solid lubricant with the ideal blend of lubrication and mechanical strength poses a formidable challenge. For the first time, we delve into synthesis and wear behavior of multicomponent 2D materials via spark plasma sintering (SPS) by mixing equimolar concentrations of hexagonal boron nitride (hBN), graphene nanoplatelets (GNPs), molybdenum disulfide (MoS2), and tungsten disulfide (WS2) using ball-milling (BM) and cryo-milling (CM) techniques. The mixing process controls the distribution of parent phases and thus solid-solutions, forming new phases, namely BCN, (Mo,W)S2, and B4C in the sample post sintering. The CM sample revealed a higher densification of 93% in contrast to the BM sample, with only 86% densification and a higher content of BCN, (Mo,W)S2, and B4C phases, exhibited via XRD and confocal Raman analysis. CM sample showed improved wear resistance (up to 46%) elicited from the lower wear volume loss (9.78 × 106 µm3) as compared to the BM sample (14.32 × 106 µm3). The dominant wear mechanisms were plowing, cracking, spallation, and severe abrasion in the BM sample, while cracking and plowing in the CM sample. The findings can pave the way for tailoring solid lubricants' compositions and wear behavior per the intended application. [ABSTRACT FROM AUTHOR]

Grease in the normal operation of the rotate vector (RV) reducer has a role that cannot be ignored, for the variable working conditions of the RV reducer, the performance of the lubricant changes directly affect its reliable operation. Therefore, the study of the rheological properties of the grease has become the focus of the study of RV reducer performance. Here, SK‐1A grease is taken as the research object, and its rheological characteristics under wide temperature range working conditions (−20–40°C) are investigated through rheological experiments to analyze the potential influence of the performance of RV reducer. However, the ordinary way of research is too complicated to better research the rheological properties of grease for a variety of working conditions. The Elman neural network (ENN) model was used to predict the rheological properties, and the results were compared with those of back propagation (BP) and radial basis function (RBF) neural networks. The results demonstrate that the ENN model demonstrates high prediction accuracy for grease rheological property prediction by comparing three types of predictions. This method can provide a theoretical reference for the accurate prediction of the rheological properties of lubricating grease affected by complex multifactors. [ABSTRACT FROM AUTHOR]

Objectives: During the insertion of cochlear implant (CI) electrode arrays, forces occur which may cause trauma and poorer hearing outcomes. Unfortunately, research groups investigating factors influencing insertion forces come to contradicting results, especially regarding insertion speed. This study was conducted to investigate the origin of these contradicting results and to determine how different testing conditions influence experimental findings. Methods: Repeated, automated insertions with three different FLEX28 CI electrode arrays (MED-EL, Innsbruck, Austria) were performed into a newly developed, anatomically correct and 3D-printed mean scala tympani phantom. The testing protocol for each electrode included variations in insertion speed (v = 0.1–2.0 mm/s) and lubrication (90%, 50%, and 10% liquid soap), resulting in 51 insertions per electrode array and a total of 153 insertions. Results: The test setup and protocol allowed for repeatable insertions with only minimal change in the morphology of the insertion force profiles per testing condition. Strong but varying dependencies of the maximal insertion forces and work were found regarding both lubrication and speed: work-speed dependency is constant for the 10% lubricant, negative for the 50% lubricant and positive for the 90% lubricant. Conclusion: Our results can explain part of the contradicting results found within previous studies by translating interrelations known from lubricated rubber friction to the field of CI electrode array insertion. We show that the main driver behind measured bulk forces are most likely the generated friction forces, which are strongly dependent on insertion speed and lubrication. The employed test setup allows for conducting repeatable and comparable insertion studies, which can be recapitulated by other centers due to the detailed explanation of the test setup as well as the developed and freely available insertion phantom. This study hence represents another important step toward standardizing CI array insertion testing. [ABSTRACT FROM AUTHOR]

Electric and magnetic fields have been used in various ways to enhance the performance of lubrication systems. The presence of these fields can significantly change the properties of lubricants. The rapid adoption of electric vehicles (EVs) has presented newlubrication-related challenges due to the presence of electric current. There is an urgent need for an in-depth study of lubrication systems subjected to such fields. This paper highlights recent research works on several key areas of lubrication involving electric or magnetic fields, which are:1) electric double layer in lubrication, 2) electrorheological fluids, 3) magnetorheological fluids, 4) ferrofluids, and 5) typical fluids used in the current EVs and typical surface failures of bearing components in EVs. Commonly used lubricants in each area are reviewed; lubrication mechanisms and related mathematical models are summarized; methods for and results from numerical analyses and experimental explorations are discussed; and common features of lubrications in different fields are explored. Based on the current research progress in these fields and the classic generalized Reynolds equation, a generalized mechanical-electro-magnetic-thermal-field (MEMT-field) Reynolds equation is proposed to describe the aforementioned lubrication scenarios and the effects of coupled mechanical, electric, magnetic, and thermal fields, which can be solved with a numerical iteration method. [ABSTRACT FROM AUTHOR]

This study addresses the challenge of enhancing lubrication performance by exploring the potential of a protic ionic liquid (IL), [Oley][Oleic], in conjunction with carbon nanotube (CNT) mixtures. The primary objective is to determine the optimal CNT concentration that achieves effective lubrication for the IL-based lubricant. Through experimental investigation, notable reductions of 19.8 % in friction and 67.2% in wear are demonstrated when [Oley][Oleic] is blended with the optimum CNT concentration at 0.10 wt%. This study employs a friction-derived adsorption model to elucidate the underlying mechanisms of friction. The results indicate that the addition of CNTs leads to a larger adsorption surface coverage area of the lubricant molecules, resulting in decreased friction and wear. Synergistic attractive cooperative interactions among the IL molecules in the presence of CNTs are identified as a key factor in enhancing adsorption efficiency. These findings provide insights into the interaction between [Oley][Oleic] and CNTs when sheared, offering a predictive framework for understanding friction and wear behaviour specific to IL-based lubricants. By presenting a solution for reducing friction and wear, this study contributes to the development of energy-efficient and environmentally-friendly lubrication practices, opening avenues for further advancements in the field of lubrication and promoting sustainable tribological solutions for diverse applications. [ABSTRACT FROM AUTHOR]

Water-based nanolubricants are widely used in rolling processes due to their unique characteristics. As a common additive, nanoparticles could significantly improve the tribological properties of the lubricant. However, the effect of the physical properties of the particles on the anti-friction behavior is unclear. In this study, the effect of Fe3O4 nanoparticles as an additive for the prepared lubricant is studied. The tribological properties of Fe3O4 water-based nanolubricant are examined using a tribometer and a scratch meter. The absorption energy is calculated using the molecular dynamic simulation method, and the best parameters for the preparation of the nanolubricant are obtained. The developed nanolubricant is used in the rolling process. The results show that the processing quality of samples is promoted and the tribological properties of water-based lubricant can be significantly promoted by an Fe3O4 nanoparticle additive. An economical and environmentally friendly method is presented through which the water-based Fe3O4 nanolubricant can be prepared for the replacement of oil-based lubricant in cold rolling strips. [ABSTRACT FROM AUTHOR]

The tribological behavior of traditional oil-in-water (O/W) lubricants (1.0 wt.%) and nano-TiO2 additive lubricants (1.0–9.0 wt.%) during micro rolling of titanium foils were analyzed. In this study, the surface morphologies of titanium foils under various lubrication conditions were assessed, and the corresponding lubrication mechanisms were revealed. The tribological behavior of nano-TiO2 additive lubricants during micro rolling of titanium foils was also explored through a series of characterization methods. The utilization of nano-TiO2 additive lubricants in micro rolling reduces the surface roughness of titanium foils. Moreover, it effectively inhibits the generation of indentations and cracks during rolling processes, enhancing the surface quality of rolled specimens. Additionally, owing to the synergism of rolling, tribo-film, mending and polishing effects of the nanoparticles, both the rolling force and surface roughness were minimized by using lubricants containing 3.0 wt.% TiO2 nanoparticles. Overall, an optimal concentration (3.0 wt.%) of TiO2 nanoparticles in water-based nanolubricants was obtained with enhanced tribological properties and lubrication performance during micro rolling of titanium foils. [ABSTRACT FROM AUTHOR]

When exposed to high surface temperatures, engine lubricating oils degrade and may form solid deposits, which cause operational issues and increase shutdown time and maintenance costs. Despite its being a common issue in engine operation, the information available on the mechanics of this phenomenon is still lacking, and the experimental data and conditions must be updated to match the improvements in both lubricant stability and engine efficiency. To this end, an experimental apparatus has been developed to study the mechanisms that lead to the degradation and deposit formation of lubricants at high temperatures. The apparatus is designed to operate at pressures up to 69 bar, surface temperatures up to 650 °C, oil bulk temperatures up to 550 °C, and flow rates of <14 mL/min. In this apparatus, the oil is cycled through a heated test section, and deposits accumulate on the heated surface. The time required for deposits to start accumulating under the test conditions is determined based on the recorded temperature traces, and collected oil and deposit samples may be analyzed to determine changes in composition over time due to high-temperature exposure. The removable test section can be modified to accommodate different geometries, surface materials, and flow paths to adapt the instrument to a range of potential research directions. This paper presents the technical details of the new apparatus and the steps taken to characterize the experimental conditions. In addition, sample data are provided to show the unique capabilities of the new instrument, and an Arrhenius plot for Castrol Perfecto X 32 in the surface temperature range of 445–475 °C is presented as a demonstration of its use for quantifying the coking delay time. The new instrument detailed herein is the first such device to demonstrate a reliable, lab-scale technique for studying lube oil coke formation and deposition at temperatures and pressures of interest to power generation gas turbines. [ABSTRACT FROM AUTHOR]

It is well known that lubricating oils reduce the friction coefficient between two surfaces in contact. Since petroleum lubricants are toxic and have a low biodegradability, they are typically not appropriate for the environment. As a result, as public worries about a pollution-free environment grow, so does the demand for lubricants that are acceptable to the environment. The primary rationale for utilizing vegetable oils in forthcoming bio-lubricant formulations is their high lubricating performance, low toxicity, sustainable, and biodegradability. Plant oils hold great potential as a foundational fluid for bio-lubricants, since their synthetic and vegetable oil-based esters provide the most environmentally friendly option for creating lubricants. In this study, Jatropha and Jojoba raw oil were chemically modified via epoxidation followed by transesterification to produce bio-lubricants. Thus, the aim of this work is to develop a bio-lubricant from jatropha and jojoba methyl ester, further adding nanoparticles multiwalled nanotubes and titanium dioxide for improvement of tribological properties. The chemical modification of the jatropha and jojoba oil results in a decrease in iodine value, resulting in the breaking of carbon bonds. Viscosity tests were performed using the Anton Par MCR 92 Rheometer, with temperature ranging from 30°C to 80°C. Thermal stability measurements of bio-lubricants were performed using PerkinElmer’s Thermogravimetric analyzer-4000 instrument and thermal degradation temperature for Epoxidized Jatropha-sulfuric acid, Epoxidized Jatropha-hydrochloric acid, Epoxidized Jojoba-sulfuric acid and Epoxidized Jojoba-Hydrochloric acid samples are 238°C, 224°C, 230°C, and 244°C, respectively. The 94.68% and 79.85% reduction in wear was obtained for Epoxidized Jojoba with hydrochloric acid, titanium dioxide and epoxidized Jatropha with sulfuric acid, multiwalled carbon nanotubes in comparison with their epoxidized samples. The coefficient of friction of Epoxidized Jatropha with sulfuric acid, multiwalled carbon nanotubes and Epoxidized Jojoba with Hydrochloric acid, Titanium dioxide sample was found to be 0.061 and 0.059, respectively [ABSTRACT FROM AUTHOR]

Purpose: Hydro-viscous drive (HVD) clutches are widely used in equipment requiring soft start, such as fans and pumps, to transmit torque and adjust speed by changing the gap distance between friction pairs. This paper aims to propose a novel two-parameter evaluation method for HVD during the mixed lubrication stage. The objective is to develop an effective model that establishes the relationship between these parameters and the actual surface topography. Design/methodology/approach: In the presented methods, the fractal features of the real manufacturing surface are calculated based on the power spectrum function by the ultra-depth three-dimensional microscope. After that, the hybrid friction model of the friction plate is established based on mixed elasto-hydrodynamic lubrication theory, boundary friction model and fractal theory. Then the torque and load bearing characteristics of the clutch are obtained, and the influences of the surface fractal features are investigated and discussed. Finally, the Weierstrass–Mandelbrot function is adopted for the surface topography characterization and evaluation. Findings: The results indicate that the proposed method exhibits good accuracy, while the speed difference between the friction pair exceeds 2,500 rpm. It is concluded that this paper proposed a way to evaluate the torque and loading capacity of HVD considering the real manufacturing surface topography and is helpful for surface optimization. Originality/value: The originality and value of this study lie in its development of a novel torque and load bearing capacity evaluation method for HVD in mixed lubrication stage, considering manufacturing surface topography and describing the real manufacturing surface. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to investigate the effect of V doping on the microstructure, chemical stability, mechanical and vacuum tribological behavior of sputtered MoS2 coatings. Design/methodology/approach: The MoS2-V coatings are fabricated via tuning V target current by magnetron sputtering technique. The structural characteristic and elemental content of the coatings are measured by field emission scanning electron microscopy, X-ray diffractometer, electron probe X-ray micro-analyzer, Raman, X-ray photoelectron spectroscopy, high resolution transmission electron microscope and energy dispersive spectrometer. The hardness of the deposited coatings are tested by a nanoindentation technique. The vacuum tribological properties of MoS2-V coatings are studied by a ball-on-disc tribometer. Findings: Introducing V into the MoS2 coatings results in a more compact microstructure. The hardness of the coatings increases with the doping of V. The MoS2-V coating deposited at a current of 0.2 A obtains the lowest friction coefficient (0.043) under vacuum. As the amount of V doping increases, the wear rate of the coating decreases first and then increases, among which the coating deposited at a current of 0.5 A has the lowest wear rate of 2.2 × 10–6 mm3/N·m. Originality/value: This work elucidates the role of V doping on the lubrication mechanism of MoS2 coatings in a vacuum environment, and the MoS2-V coating is expected to be applied as a solid lubricant in space environment. [ABSTRACT FROM AUTHOR]

Friction blisters are a common injury of the feet sustained by individuals participating in sporting, recreational, and military activities. The high incidence of friction blisters brings into question the effectiveness of common prevention strategies. The purpose of this article was to review current evidence for established blister-prevention strategies and to explore how these interventions address the factors that cause friction blisters. Preventive strategies, focusing on previously overlooked elements of the blister-causing mechanism, are proposed. Areas of future research that are much needed to reduce this common skin injury in active individuals are outlined. [ABSTRACT FROM AUTHOR]

Supramolecular gelator functionalized liquid metal (Gelator@GLM) exhibited excellent tribological properties due to the synergistic effect of GLM nanodroplets and the gel generating protective film. [Display omitted] • Supramolecular gelator functionalized liquid metal nanodroplets were prepared by self-assembly and radical polymerization. • The Gelator@GLM nanodroplets displayed effective anti-wear and friction reduction properties as lubricant additives. • The lubrication performance is attributed to the synergistic effect of GLM nanodroplets and the gel generating protective film. In this work, dopamine n -butenylamide (DBA) modified GLM nanodroplets were prepared via directional ultrasound of bulk liquid metal in ethanol aqueous solution as well as DBA self-assembly, followed by grafting with urea-based gelators via radical polymerization to obtain GLM-based supramolecular gelators (Gelator@GLM). The grafting gelators can impart their good compatibility between the GLM nanodroplets and the base oil, so that the Gelator@GLM nanodroplets can be dispersed in the base oil uniformly and stably for more than 3 weeks. Meanwhile, the tribological properties of Gelator@GLM nanodroplets was significantly enhanced, with a reduction of coefficient of friction (COF) and the wear volume of 41.18% and 92.13%, respectively, when compared with the base oil. Furthermore, Gelator@GLM additives exhibited stable lubrication performance even under variable temperature and frequency conditions. The synergistic effect of GLM nanodroplets and the gels generating a physical adsorption film and a chemically protective film (containing iron and chromium oxides, nitrides and carbides) can be credited with the improved tribological performance. [ABSTRACT FROM AUTHOR]

Reducing friction between drill string and wellbore wall is one of the key functions of drilling fluid which may result from tight holes, key seats, differential sticking, or cutting build up along the drill string. However due to growing environmental concerns, biodegradable lubricants which are also cost-efficient are appreciated and mandated in many countries. This study discusses the performance analysis of biodegradable biodiesel produced from pomelo peels and Petroleum-based lube oil as drilling fluid lubricants. The test samples comprise 700 mL of water + 10 % bentonite + 3 % barite + 0.25 % CaCO3 + 0.25 % KOH + 1 % CMC + lubricant. Two sets of lubricants were utilized to prepare 10 samples of drilling fluid, one set with petroleum-based lubricant and other with biodiesel. Essential oil was extracted from pomelo peel with the help of the Clevenger apparatus. The oil was then converted to biodiesel through the process of transesterification. Biodiesel properties were tested for the ASTM standards. Both sets of drilling fluid samples were tested for their rheological, filtration and lubricating properties and from the results obtained it can be concluded that both type of lubricating agents have almost negligible impact on rheological and filtration loss properties. However, the lubricity coefficient values drastically decreased as we increased the lubricant content, which is an indication that biodiesel extracted from pomelo peel acts as a better lubricant. The values of the lubricity coefficient for biodiesel based drilling fluid also fell well within the advised range (<0.30). We can therefore draw the conclusion that biodiesel made from pomelo peel can replace petroleum-based lubricants while also lowering the environmental concerns related to lubricants. [ABSTRACT FROM AUTHOR]

A novel aerosol evaluation cell was employed to measure particle number and mass concentration, with a size distribution from nano to micro scale. Different cooling/lubrication and airflow extraction scenarios were tested on a CFRP/Ti6Al4V case study, and the particle concentrations were measured to evaluate their effect on productivity and cost per hole, if current occupational exposure limits are respected. Aspects to achieve sustainable machining like tool life, consumption of coolant and energy, and standby time required to safely open the machine-tool doors were considered. LCO 2 delivered the best productivity and cost results as it improved the tool life by 40 % compared to MQL, while eliminating the need for standby time to evacuate particles. [ABSTRACT FROM AUTHOR]

The complexity of sheet metal parts has reached a level, that without supporting process planning applications almost impossible to design the process planning. Because technology is sharpened to the limit the slightest disturbance in the production results in a waste product. The lubrication condition used during the sheet metal forming is crucial to the success of production. Therefore, the need to model the resulting tribological system as accurately as possible has become increasingly important. This paper purpose with the physically based measurement of the so-called enhanced Coulomb model material parameter used in AutoForm software and the analysis of its effect. [ABSTRACT FROM AUTHOR]

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